That's what they ARE. They're a site that collects movie reviews from all over the world. Their numbers are the average of all the opinions of the biggest movie critics in the country and in the world. They also publish their user reviews in addition to the published ones.
They do criticize, but the less tomatoes they throw, the more they endorse the film. And that's no different than a review site than gives stars.
Tomatoes, tomahtos.
Stars, stahrs.
They are critics that is there job they get paid for. I do think they are really harsh on movies but thats why they are called critics.
Its so you know which movies are crappy and which are worth seeing.
For some reason, I think they're really useless. All they do is criticize movies.